Method and post structures for interferometric modulation

Abstract

An interferometric modulator includes a post structure comprising an optical element. In a preferred embodiment, the optical element in the post structure is a reflective element, e.g., a mirror. In another embodiment, the optical element in the post structure is an etalon, e.g., a dark etalon. The optical element in the post structure may decrease the amount of light that would otherwise be retroreflected from the post structure. In various embodiments, the optical element in the post structure increases the brightness of the interferometric modulator by redirecting light into the interferometric cavity. For example, in certain embodiments, the optical element in the post structure increases the backlighting of the interferometric modulator.

What is claimed is: 
     
       1. An interferometric modulator comprising a first mirror and a second mirror that define an optical cavity that produces optical interference that can be modulated, at least one of said first and second mirrors supported by a post structure, wherein the post structure comprises an optical element. 
     
     
       2. The interferometric modulator of  claim 1  in which the optical element is one mirror of an etalon. 
     
     
       3. The interferometric modulator of  claim 2  in which the etalon is a dark etalon. 
     
     
       4. The interferometric modulator of  claim 1  in which the optical element is configured to deflect light. 
     
     
       5. The interferometric modulator of  claim 1  in which the optical element is configured to reflect light. 
     
     
       6. The interferometric modulator of  claim 1  in which the optical element is configured to scatter light. 
     
     
       7. The interferometric modulator of  claim 1  in which the optical element comprises a reflective surface. 
     
     
       8. The interferometric modulator of  claim 7  in which the reflective surface is configured to direct light into an interferometric cavity of the interferometric modulator. 
     
     
       9. The interferometric modulator of  claim 8  in which the reflective surface is configured to increase backlighting of the interferometric modulator. 
     
     
       10. The interferometric modulator of  claim 8  in which the post structure further comprises a dark etalon. 
     
     
       11. The interferometric modulator of  claim 8  in which the reflective surface is configured to increase brightness of the interferometric modulator. 
     
     
       12. The interferometric modulator of  claim 1  in which the second mirror is movable. 
     
     
       13. A method for making an interferometric modulator, comprising:
 depositing a reflective layer onto a substrate to form a first mirror; 
 depositing a sacrificial layer over the first mirror; 
 forming apertures in the sacrificial layer; 
 depositing post material into the apertures; 
 forming an optical element over the post material; 
 forming a moveable second mirror over the sacrificial layer and the optical element; and 
 removing the sacrificial layer to thereby form an interferometric cavity. 
 
     
     
       14. The method of  claim 13  in which forming the optical element comprises tapered etching. 
     
     
       15. The method of  claim 13  in which forming the optical element comprises forming a structure selected from the group consisting of reflector, etalon, and a microlens. 
     
     
       16. An interferometric modulator made by the method of  claim 13 .